1. Field of the Invention
The present invention relates to a transmission apparatus on which a plurality of communication units, including communication units that can communicate at high speed, can be mounted.
2. Description of Related Art
Recent years have seen the proliferation of mobile communication systems that can perform voice and data communication from wireless terminals by performing wireless communication between a wireless terminal such as a mobile telephone or mobile electronic device and a mobile base station. In order for mobile operators to expand the area in which communication is possible along with the rapid spread of mobile telephones, wireless base stations have been newly installed in communication areas that mobile base stations cannot cover, that is to say, dead zones.
Conventionally, communication among a plurality of radio base stations and communication between a radio line control station that controls this plurality of radio base stations and a radio base station is generally performed via a wired network such as an underground optical cable network. However, in order to build such a wired network, immense equipment investment is required.
Therefore, in recent years, by adopting a method that wirelessly performs communication among radio base stations and communication between a radio base station and a radio line control station, attempts have been made to construct a mobile communication system easier, faster and at a lower cost compared to a wired network.
In such radio communication, for example a compact microwave communication system is utilized. A microwave communication system has an outdoor apparatus such as an antenna, and an indoor apparatus that has a transmission apparatus that processes microwaves that have been received (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2006-197343).
The transmission apparatus that constitutes the microwave communication system houses within one case a communication unit that is capable of radio communication and a communication unit that is capable of optical communication that is faster than radio communication. Thereby, since the wiring has a higher density, there are problems such as malfunctioning of the transmission apparatus due to this higher density.